hi, I naturally have a large lower body that gains muscle mass easily and a skinny upper body that struggles to gain muscle mass,im trying to have a large upper and ive been working on my upper body for months in the gym, and my upper body is now able to lift heavier weights like 20kg for bicep curl and 15kg for tricep extensions,etc however my upper body still hasnt gained much muscle mass, and is still skinny, i feel its because my lower body is gaining most of the mass and my upper body is gaining only the strength. and I no its not my diet because i eat lots of oats, carbohydrates and proteins, and I no im pumping the weights properly i pump under supervision of other big bodybuilders in the gym.